Minimally invasive glaucoma surgical instrument and method

ABSTRACT

A surgical instrument and methods for the treatment of glaucoma are provided. The instrument uses either cauterization, a laser to ablate, sonic or ultrasonic energy to emulsify, or mechanical cutting of a portion of the trabecular meshwork. The instrument may also be provided with irrigation, aspiration, and a footplate. The footplate is used to enter Schlemm&#39;s canal, serves as a guide, and also protects Schlemm&#39;s canal.

CROSS-REFERENCE TO THE RELATED APPLICATIONS

This application claims priority to U.S. Provisional Application Ser.No. 60/263,617, filed Jan. 18, 2001, the disclosure of which is hereinincorporated by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a new glaucoma surgical instrument andmethod, and, in particular, removal of the trabecular meshwork bymechanical cautery, vaporization or other tissue destruction meansoptionally coupled to an instrument with infusion, aspiration, and afootplate.

2. Description of the Related Art

Aqueous is a clear, colorless fluid that fills the anterior andposterior chambers of the eye. The aqueous is formed by the ciliary bodyin the eye and supplies nutrients to the lens and cornea. In addition,the aqueous provides a continuous stream into which surrounding tissuescan discharge the waste products of metabolism.

The aqueous produced in the ciliary process circulates from theposterior chamber to the anterior chamber of the eye through the pupiland is absorbed through the trabecular meshwork, a plurality ofcrisscrossing collagen cords covered by endothelium. Once through thetrabecular meshwork, the aqueous passes through Schlemm's canal intocollector channels that pass through the scleral and empty into theepiscleral venous circulation. The rate of production in a normal eye istypically 2.1 μL/min. Intraocular pressure in the eye is maintained bythe formation and drainage of the aqueous. All the tissues within thecorneoscleral coat covering the eyeball are subject to this pressure,which is higher than pressure exerted on tissues at other locations inthe body.

Glaucoma is a group of diseases characterized by progressive atrophy ofthe optic nerve head leading to visual field loss, and ultimately,blindness. Glaucoma is generally associated with elevated intraocularpressure, which is an important risk factor for visual field lossbecause it causes further damage to optic nerve fibers. Other causes ofglaucoma may be that the nerve is particularly vulnerable to thepressure due to poor local circulation, tissue weakness or abnormalityof structure. In a “normal” eye, intraocular pressure ranges from 10 to21 mm mercury. In an eye with glaucoma, this pressure can rise to asmuch as 75 mm mercury.

There are several types of glaucoma, including open and closed angleglaucoma, which involve the abnormal increase in intraocular pressure,primarily by obstruction of the outflow of aqueous humor from the eye,or, less frequently, by over production of aqueous humor within the eye.The most prevalent type is primary open angle glaucoma in which theaqueous humor has free access to the irridocorneal angle, but aqueoushumor drainage is impaired through obstruction of the trabecularmeshwork. In contrast, in closed angle glaucoma, the irridocorneal angleis closed by the peripheral iris. The angle block can usually becorrected by surgery. Less prevalent types of glaucoma include secondaryglaucomas related to inflammation, trauma, and hemorrhage.

Aqueous humor is similar in electrolyte composition to plasma, but has alower protein content. The aqueous humor keeps the eyeball inflated,supplies the nutritional needs of the vascular lens and cornea andwashes away metabolites and toxic substances within the eye. The bulk ofaqueous humor formation is the product of active cellular secretion bynonpigmented epithelial cells of the ciliary process from the activetransport of solute, probably sodium, followed by the osmotic flow ofwater from the plasma. The nonpigmented epithelial cells of the ciliaryprocess are connected at their apical cell membranes by tight junctions.These cells participate in forming the blood/aqueous barrier throughwhich blood-borne large molecules, including proteins, do not pass.

Intraocular pressure (IOP) is a function of the difference between therate at which aqueous humor enters and leaves the eye. Aqueous humorenters the posterior chamber by three means: 1) active secretion bynonpigmented epithelial cells of the ciliary process; 2) ultrafiltrationof blood plasma; and 3) diffusion. Newly formed aqueous humor flows fromthe posterior chamber around the lens and through the pupil into theanterior chamber; aqueous humor leaves the eye by 1) passive bulk flowat the irridocorneal angle by means of the uveloscleral outflow, or by2) active transportation through the trabecular meshwork, specificallythe juxta canalicar portion. Any change in 1), 2), or 3) will disturbaqueous humor dynamics and likely alter intraocular pressure.

Primary open angle glaucoma is caused by a blockage in the trabecularmeshwork. This leads to an increase in intraocular pressure. The majorobstruction is at the juxta-canalicular portion which is situatedadjacent to Schlemm's canal. In infants a goniotomy or a trabeculotomycan be performed. In goniotomy or trabeculotomy a small needle or probeis introduced into Schlemm's canal and the trabecular meshwork ismechanically disrupted into the anterior chamber. Approximately 90°–120°of trabecular meshwork can be disrupted. The anatomical differencebetween congenital glaucoma and adult glaucoma is that in congenitalglaucoma the ciliary body muscle fibers insert into the trabecularmeshwork and once disrupted the trabecular meshwork is pulledposteriorly allowing fluid to enter Schlemm's canal and to be removedthrough the normal collector channels that are present in the wall ofSchlemm's canal. In adults the trabecular meshwork tears but remainsintact and reattaches to the posterior scleral wall of Schlemm's canalblocking the collector channels.

Most treatments for glaucoma focus on reducing intraocular pressure.Treatment has involved administration of beta-blockers such as timololto decrease aqueous humor production, adranergic agonists to lowerintraocular pressure or diuretics such as acetazolamide to reduceaqueous production, administration of miotic eyedrops such aspilocarpine to facilitate the outflow of aqueous humor, or prostaglandinanalogs to increase uveoscleral outflow. Acute forms of glaucoma mayrequire peripheral iridectomy surgery to relieve pressure where drugtherapy is ineffective and the patient's vision is at immediate risk.Other forms of treatment have included physical or thermal destruction(“cyclo-destruction”) of the ciliary body of the eye, commonly bysurgery or application of a laser beam, cryogenic fluid or highfrequency ultrasound.

In guarded filtration surgery (trabeculectomy), a fistula createdthrough the limbal sclera is protected by an overlying partial thicknesssutured scleral flap. The scleral flap provides additional resistance toexcessive loss of aqueous humor from the eyeball, thereby reducing therisk of early postoperative hypotony.

In accordance with one recently introduced procedure, a full thicknessfiltering fistula may be created by a holmium laser probe, with minimalsurgically induced trauma. After retrobulbar anesthesia, a conjunctivalincision (approximately 1 mm) is made about 12–15 mm posterior to theintended sclerostomy site, and a laser probe is advanced through thesub-conjunctival space to the limbus. Then, multiple laser pulses areapplied until a full thickness fistula is created. This technique hassometimes resulted in early hypotony on account of a difficulty incontrolling the sclerostomy size. In addition, early and late irisprolapse into the sclerostomy has resulted in abrupt closure of thefistula and eventual surgical failure. Further, despite its relativesimplicity, the disadvantage of this procedure, as well as other typesof glaucoma filtration surgery, is the propensity of the fistula to besealed by scarring.

Various attempts have been made to overcome the problems of filtrationsurgery, for example, by using ophthalmic implant instruments such asthe Baerveldt Glaucoma Implant. Typical ophthalmic implants utilizedrainage tubes so as to maintain the integrity of the openings formed inthe eyeball for the relief of the IOP.

Typical ophthalmic implants suffer from several disadvantages. Forexample, the implants may utilize a valve mechanism for regulating theflow of aqueous humor from the eyeball; defects in and/or failure ofsuch valve mechanisms could lead to excessive loss of aqueous humor fromthe eyeball and possible hypotony. The implants also tend to clog overtime, either from the inside by tissue, such as the iris, being suckedinto the inlet, or from the outside by the proliferation of cells, forexample by scarring. Additionally, the typical implant insertionoperation is complicated, costly and takes a long time and is reservedfor complicated glaucoma problems.

There are many problems, however, in effectively treating glaucoma withlong term medicinal or surgical therapies. One problem is the difficultyin devising means to generate pharmacologically effective intraocularconcentrations and to prevent extraocular side effects elicited by asystemic administration. Many drugs are administered topically orlocally. The amount of a drug that gets into the eye is, however, only asmall percentage of the topically applied dose because the tissues ofthe eye are protected from such substances by numerous mechanisms,including tear turnover, blinking, conjunctival absorption into systemiccirculation, and a highly selective corneal barrier.

Pharmacological treatment is prohibitively expensive to a large majorityof glaucoma patients. In addition, many people afflicted with thedisease live in remote or undeveloped areas where the drugs are notreadily accessible. The drugs used in the treatment often haveundesirable side effects and many of the long-term effects resultingfrom prolonged use are not yet known. Twenty-five percent of patients donot use their medications correctly.

Glaucoma is a progressively worsening disease, so that a filtrationoperation for control of intraocular pressure may become necessary.Present surgical techniques to lower intraocular pressure, whenmedication fails to decrease fluid flow into the eye or to increasefluid outflow, include procedures that permit fluid to drain from withinthe eye to extraocular sites by creating a fluid passageway between theanterior chamber of the eye and the potential supra-scleral/sub-Tenon'sspace, or, alternatively, into or through the Canal of Schlemm (see,e.g., U.S. Pat. No. 4,846,172). The most common operations for glaucomaare glaucoma filtering operations, particularly trabeculectomy. Theseoperations involve creation of a fistula between the subconjunctivalspace and the anterior chamber. This fistula can be made by creating ahole at the limbus by either cutting out a portion of the limbal tissueswith either a scalpel blade or by burning with a cautery through thesubconjunctival space into the anterior chamber. Fluid then filtersthrough the fistula and is absorbed by episcleral and conjunctival. Inorder for the surgery to be effective, the fistula must remainsubstantially unobstructed. These drainage or filtering procedures,however, often fail by virtue of closure of the passageway resultingfrom the healing of the very wound created for gaining access to thesurgical site. Failures most frequently result from scarring at the siteof the incisions in the conjunctiva and the Tenon's capsule. The surgeryfails immediately in at least 15% of patients, and long term in a muchhigher percentage. Presently, this consequence of trabeculectomy,closure of the passageway, is treated with 5-fluorouracil andMitomycin_(—)C, which apparently prevent closure by inhibiting cellularproliferation. These drugs, however, are highly toxic and haveundesirable side effects, including scleral melting, hypotony, leaks,and late infections.

Other surgical procedures have been developed in an effort to treatvictims of glaucoma. An iridectomy, removal of a portion of the iris, isoften used in angle-closure glaucoma wherein there is an occlusion ofthe trabecular meshwork by iris contact. Removal of a piece of the iristhen gives the aqueous free passage from the posterior to the anteriorchambers in the eye. The tissue of the eye can grow back to thepre-operative condition, thereby necessitating the need for furthertreatment.

In view of the limited effectiveness of treatment options, there is,therefore, a need to develop more effective treatments for glaucoma.

SUMMARY OF THE INVENTION

The present invention is a surgical instrument and minimally invasivesurgical method to remove at least a portion of the trabecular meshworkof the eye, providing for aqueous drainage in the treatment of glaucoma.

A preferred embodiment of the present invention involves inserting asurgical instrument through a small corneal incision transcamerallyunder direct visualization to ablate the trabecular meshwork. Theinstrument may include a foot plate, such that the instrument canpenetrate the trabecular meshwork into Schlemm's canal. The footplatemay also act as a protective device for the endothelial cells andcollector channels lining the scleral wall of Schlemm's canal. Theinstrument may also comprise an infusion system and aspiration system.Infusion maintains and deepens the anterior chamber so that easy accessof the angle of the eye is obtained to the trabecular meshwork andSchlemm's canal. Infusion also allows fluid to flow out to the collectorchannels whilst the surgery is being performed, thus keeping thesurgical site blood free. Aspiration is designed to remove ablatedtissue, gas and bubble formation, and all intraocular debris generated.The aspiration may be directly linked to either a cutting mechanism,such as a guillotine cutting machine, laser probe, a piezo-electriccrystal producing sonic or ultrasonic energy, or cautery element. Thesemodalities are capable of substantially complete tissue removal bymechanical means, cautery, vaporization, or other tissue destructiontechniques.

The surgical instrument is used to perform a goniectomy procedure, byremoving a portion of the trabecular meshwork consisting of thepigmented trabecular meshwork, allowing free access of aqueous from theanterior chamber through to the scleral portion of Schlemm's canal thatcontains the endothelial cells and most importantly the collectorchannels that lead back to the episcleral venous system.

In another embodiment, a Schlemmectomy surgical procedure, similar to atrabeculotomy, a schlemmectomy probe is inserted into Schlemm's canalunder direct visualization through a scleral incision, such that thesurface of the instrument faces the trabecular meshwork and the tissuecomprising the pigmented and a portion of the non-pigmented trabecularmeshwork facing into Schlemm's canal is removed by a cautery element,radio-frequency electrode, or an ultrasound transducer formed from apiezo-electric crystal.

This instrument is advantageous because it combines existing procedureswith new technology, providing a simple solution for glaucoma treatment.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross sectional schematic diagram of a human eye.

FIG. 2 is a cross sectional schematic diagram which shows aqueous flowinto and through the anterior chamber in a human eye.

FIGS. 3 a–d shows diagrammatically the progression of the deformation ofthe lamina cribrosa in glaucoma.

FIGS. 4 a–c show diagrammatically the steps of performing a goniectomy.

FIGS. 5 a–d show diagrammatically the steps of performing atrabeculodialysis.

FIGS. 6 a–f show diagrammatically the steps of a trabeculotomy procedureusing a probe of a preferred embodiment.

FIG. 7 is a perspective view which shows a goniectomy cautery probe of apreferred embodiment.

FIG. 8 is a cross-sectional schematic diagram which shows the goniectomycautery probe of FIG. 7.

FIG. 9 is a cross sectional schematic diagram which shows anotherembodiment of the goniectomy cautery probe of FIG. 7.

FIG. 10 a is a detailed view which shows the probe tip of the goniectomycautery probe of FIG. 7.

FIG. 10 b is a cross-sectional schematic diagram which shows the probetip of the goniectomy cautery probe of FIG. 7.

FIG. 11 a is a detailed view which shows the probe tip of the goniectomycautery probe of FIG. 7.

FIG. 11 b is a cross-sectional schematic diagram which shows the probetip of the goniectomy cautery probe of FIG. 7.

FIG. 12 a is a detailed view which shows the probe tip of the goniectomycautery probe of FIG. 7.

FIG. 12 b is a cross-sectional schematic diagram which shows the probetip of the goniectomy cautery probe of FIG. 7.

FIG. 13 is a perspective view which shows a goniectomy cautery probe ofa preferred embodiment.

FIG. 14 is a perspective view which shows a goniectomy cautery probe ofa preferred embodiment.

FIG. 15 a is a detailed view which shows the probe tip of the goniectomycautery probe of FIG. 13.

FIG. 15 b is a cross-sectional schematic diagram which shows the probetip of the goniectomy cautery probe of FIG. 13.

FIG. 16 a is a detailed view which shows the probe tip of the cauteryprobe of FIG. 14.

FIG. 16 b is a cross-sectional schematic diagram which shows the probetip of the cautery probe of FIG. 14.

FIG. 17 shows a schematic of a circuit diagram of a preferred embodimentof a goniectomy probe.

FIG. 18 is a perspective view which shows a goniectomy probe.

FIG. 19 is a cross-sectional schematic diagram which shows an embodimentof the probe of FIG. 18.

FIG. 20 is a cross-sectional schematic diagram which shows an embodimentof the probe of FIG. 18.

FIG. 21 is a cross-sectional schematic diagram which shows an embodimentof the probe of FIG. 18.

FIG. 22 is a cross-sectional schematic diagram which shows an embodimentof the probe of FIG. 18.

FIG. 23 is a cross-sectional schematic diagram which shows an embodimentof the probe of FIG. 18.

FIG. 24 a is a perspective view which shows a preferred embodiment of alaser goniectomy probe.

FIG. 24 b is a perspective view which shows a preferred embodiment of alaser goniectomy probe.

FIG. 25 is a cross sectional schematic diagram of the laser goniectomyprobe of FIG. 24 a.

FIG. 26 is a cross sectional schematic diagram of the laser goniectomyprobe of FIG. 24 b.

FIG. 27 is a cross sectional schematic diagram of the laser goniectomyprobe of FIG. 24 b.

FIG. 28 is a perspective view which shows a Schlemmectomy probe of apreferred embodiment.

FIGS. 29 a–c are detailed views which show the probe tip of the probe ofFIG. 28.

FIG. 30 is a perspective view of an alternative preferred embodiment ofthe probe of FIG. 28.

FIGS. 31 a,b,c are detailed views of the probe tip of FIG. 30.

FIGS. 32 a,b are detailed views which show the probe tip of the probe ofFIG. 30.

FIG. 33 a is a detailed view which shows the probe tip of the probe ofFIG. 30.

FIG. 33 b is a cross-sectional schematic diagram which shows the probetip of the probe of FIG. 30.

FIG. 34 a is a detailed view which shows the probe tip of the probe ofFIG. 30.

FIG. 34 b is a cross-sectional schematic diagram which shows the probetip of the probe of FIG. 30.

FIG. 35 a is a detailed view which shows the probe tip of the probe ofFIG. 30.

FIG. 35 b is a cross-sectional schematic diagram which shows the probetip of the probe of FIG. 30.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIG. 1, relevant structures of the eye will be brieflydescribed, so as to provide background for the anatomical terms usedherein. Certain anatomical details, well known to those skilled in theart, have been omitted for clarity and convenience.

As shown in FIG. 1, the cornea 103 is a thin, transparent membrane whichis part of the outer eye and lies in front of the iris 104. The cornea103 merges into the sclera 102 at a juncture referred to as the limbus108. A layer of tissue called bulbar conjunctiva 106 covers the exteriorof the sclera 102. The bulbar conjunctiva 106 is thinnest anteriorly atthe limbus 108 where it becomes a thin epithelial layer which continuesover the cornea 103 to the corneal epithelium. As the bulbar conjunctiva106 extends posteriorly, it becomes more substantial with greateramounts of fibrous tissue. The bulbar conjunctiva 106 descends overTenon's capsule approximately 3 mm from the limbus 108. Tenon's capsuleis thicker and more substantial encapsulatory tissue which covers theremaining portion of the eyeball. The subconjunctival and sub-Tenon'scapsule space become one when these two tissues meet, approximately 3 mmfrom the limbus. The ciliary body or ciliary process 110 is part of theuveal tract. It begins at the limbus 108 and extends along the interiorof the sclera 102. The choroid 112 is the vascular membrane whichextends along the retina back towards the optic nerve. The anteriorchamber 114 of the eye is the space between the cornea 103 and acrystalline lens 116 of the eye. The crystalline lens of the eye issituated between the iris 104 and the vitreous body 120 and is enclosedin a transparent membrane called a lens capsule 122. The anteriorchamber 114 is filled with aqueous humor 118. The trabecular meshwork121 removes excess aqueous humor 118 from the anterior chamber 114through Schlemm's canal 124 into collector channels which merge withblood-carrying veins to take the aqueous humor 118 away from the eye.

As shown in FIG. 2, the flow of aqueous 118 is from the posteriorchamber, through the pupil, into the anterior chamber 114.

FIGS. 3 a–d show longitudinal sections through the optic nerve head,illustrating the progressive deepening of the cup 302 in the nerve headfrom normal to advanced glaucoma. FIG. 3 a shows a normal nerve and FIG.3 d shows an effected nerve in advanced glaucoma. As the cup 302 deepensand the lamina cribrosa 306 becomes more curved, axons 304 passingthrough the lamina 306 are subject to kinking and pressure as they maketheir way through the lamina 306.

Goniotomy

FIGS. 4 a–c show the steps for performing a goniotomy procedure. Asshown in FIG. 4 a, locking forceps 406 are typically used to grasp theinferior and superior rectus muscles. A goniotomy lens 408 is positionedon the eye. A goniotomy knife 400 is inserted from the temporal aspectbeneath the goniotomy lens and viewed through a microscope. The corneais irrigated with balanced salt solution. The surgeon positions thegoniotomy lens 408 on the cornea, holding the lens 408 with an angled,toothed forceps 406 placed into the two dimples at the top of the lens408.

The surgeon places the goniotomy knife 400 into and through the cornea1.0 mm anterior to the limbus, maintaining the knife 400 parallel to theplane of the iris (FIG. 4 b). Slight rotation of the knife 400facilitates smooth penetration into the anterior chamber without asudden break through the cornea. The surgeon continues to gently applypressure and rotate the goniotomy knife 400, directing it across thechamber, parallel to the plane of the iris, until reaching thetrabecular meshwork in the opposite angle.

The surgeon visualizes the trabecular meshwork under direct microscopyand engages the superficial layers of the meshwork at the midpoint ofthe trabecular band. The incision is typically made 100° to 120°, asdesignated by αin FIG. 4 b, circumferentially, first incising clockwise50° to 60°, then counterclockwise for 50° to 60°.

As the tissue is incised, a white line can be seen and the iris usuallydrops posteriorly. An assistant facilitates incision by rotating the eyein the opposite direction of the action of the blade (FIG. 4 c).

The surgeon completes the goniotomy incision and promptly withdraws theblade. If aqueous escapes from the wound and the chamber is shallow, thesurgeon can slide the goniotomy lens over the incision as the blade iswithdrawn. The anterior chamber can be reformed with an injection ofbalanced salt solution through the external edge of the cornealincision. The leak can be stopped using a suture and burying the knot.

Trabeculodialysis

Trabeculodialysis is similar to goniotomy but is performed primarily inyoung patients with glaucoma secondary to inflammation.Trabeculodialysis differs from goniotomy only in the position of theincision. FIGS. 5 a–d show the steps of a trabeculodialysis procedure.The knife 500 passes across the anterior chamber and engages thetrabecular meshwork at Schwalbe's line rather than at the midline of themeshwork, as shown in FIG. 5 a.

The incision is typically made 100° to 120° circumferentially, asdesignated by α in FIG. 5 b, first incising clockwise 50° to 60°, thencounterclockwise for 50° to 60° (FIG. 5 b).

With the flat side of the blade, the surgeon pushes the trabecularmeshwork inferiorly toward the surface of the iris, as shown in FIG. 5c. FIG. 6 d shows the meshwork, disinserted from the scleral sulcus,exposing the outer wall of Schlemm's canal.

Trabeculotomy

Trabeculotomy displaces trabecular meshwork as a barrier to aqueousoutflow. Initially, the surgeon creates a triangular scleral flap 604that is dissected anteriorly of the limbus, as shown in FIG. 6 a. Aradial incision is made over the anticipated site of Schlemm's canal(FIG. 6 b). The incision is deepened until the roof of Schlemm's canalis opened (FIG. 6 c).

The surgeon locates Schlemm's canal through the external surface of thelimbus, threads a trabeculotome 600 into the canal and rotates theinstrument into the anterior chamber, as shown in FIG. 6 d. The upperarm 610 of the instrument should be kept parallel to the plane of theiris. The instrument 600 is then rotated within the anterior chamber andmaintained parallel to the iris. After rotating the instrument 600through the meshwork in one direction, the surgeon withdraws theinstrument and inserts a second instrument with the opposite curve. Theidentical procedure is then performed in the opposite direction.

Collapse of the anterior chamber often occurs during the procedure. Thechamber can be reformed by injecting irrigation fluid. Aspiration may beused to remove the tissue. The scleral flap 604 may then be suturedclosed, as shown in FIG. 6 e.

Goniectomy Cauterization Probe

A preferred embodiment of a goniectomy probe, used to cauterize andablate the trabecular meshwork is shown in FIGS. 7 and 8. The probe 700comprises a handle 705 and a probe tip 710. Preferably, the handle isapproximately 20 gauge and the probe tip is approximately 27 gauge. Theproximal end of the handle is adapted for mating with a connector 712 tothe output terminals of an energy source 760.

The probe also includes electrical leads 834 (FIG. 8), a power cable708, preferably a coaxial cable, and actuation means. These componentsextend from the handle 705, through an electrical lead lumen 832 (FIG.8) in the probe shaft 705, to the corresponding components of the probe700 disposed on the distal end. The proximal ends of the cables andlumens connect to the corresponding connectors that extend from thedistal end of the probe handle 705.

Aspiration and irrigation may be provided by an aspiration pump 770 andirrigation pump 780. The aspiration pump 770 is connected to a standardvacuum supply line to promote the withdrawal of the aspiration fluid.Aspiration vacuum control may be provided by an aspiration valve. In apreferred embodiment, as shown in FIG. 8, both irrigation and aspirationmay be provided by the same lumen 822, alternating the pump as needed.However, the irrigation lumen 922 and aspiration lumen 924 are separatein the embodiment of FIG. 9, providing for simultaneous irrigation andaspiration. Irrigation under pressure flushes blood from the eye andexpands the anterior chamber, providing more room for the procedure.

The handle 705 may be made of an electrically insulating polymericmaterial, configured in a pencil-shape form having a cylindrical bodyregion 702 and a tapered forward region 704. A contoured handle helps toreduce the holding force required and increase proprioceptivesensitivity. Although a pencil-shape configuration is preferred, it isnoted that any configuration of the handle 705 which is easily,comfortably and conveniently grasped by the operator will also besuitable and is considered to be within the scope of the presentinvention.

The probe tip 710 is connected to the main body of the handle 705. Theprobe tip further comprises a footplate 721, which protects thecollector channels, penetrates the trabecular meshwork, and serves as aguide in Schlemm's canal. The cautery element 730, located at the distalend of the probe tip 710 may have a variety of configurations.

The tip 710 may be any material, such as titanium, brass, nickel,aluminum, stainless steel, other types of steels, or alloys.Alternatively, non-metallic substances may also be used, such as certainplastics. The malleable probe tips can be configured as straight, angledor curved, for example, which provides for optimal access to specificanatomy and pathology. Unique tip designs improve tactile feedback foroptimal control and access, and provide for improved tissuevisualization with greatly reduced bubbling or charring.

The probe tip 710 comprises an electrode 730, suitable for cautery, asknown to those of skill in the art. Various electrode configurations andshapes may be suitable. The cautery element 730 may be any electrodethat may provide ablation or cauterization of tissue, such as anultrasound transducer, a RF electrode, or any other suitable electrode.

The cautery element may also include other cautery energy sources orsinks, and particularly may include a thermal conductor. Examples ofsuitable thermal conductor arrangements include a metallic element whichmay, for example, be constructed as previously described. However, inthe thermal conductor embodiment such a metallic element would begenerally resistively heated in a closed loop circuit internal to theprobe, or conductively heated by a heat source coupled to the thermalconductor.

The probe tip may have a coating such as a non-stick plastic or acoating comprising diamond to prevent undesirable sticking or charringof tissue. The electrode may be provided on the inner surface of thetip. Alternatively, the electrode is embedded in a sheath of a tube.Insulation is provided around the cautery element so that other areas ofthe eye are not affected by the cauterization. A sleeve shield or anon-conductive layer may be provided on the probe tip to expose only aselected portion of the electrode. The sleeve preferably has sufficientthickness to prevent both current flow and capacitance coupling with thetissue.

The electrode or other device used to deliver energy can be made of anumber of different materials including, but not limited to stainlesssteel, platinum, other noble metals, and the like. The electrode canalso be made of a memory metal, such as nickel titanium. The electrodecan also be made of composite construction, whereby different sectionsare constructed from different materials.

In a preferred embodiment, the probe assembly is bipolar. In a bipolarsystem, two electrodes of reversed polarity are located on the probetip, thus eliminating the contact plate for completion of the circuit.Additionally, any number of pairs of electrodes may be provided on theprobe tip.

In an alternative embodiment, the probe assembly is monopolar. In amonopolar system, the system comprises a single electrode and a contactplate is attached to the surface of the human body. The contact plate isfurther connected to the minus terminal of the power source via a leadwire. Voltages of reversed polarity are applied to the electrode and thecontact plate.

In a preferred embodiment as shown in FIGS. 10 a and 10 b, an electrodeassembly of a bipolar probe includes one electrode 1020 made from astainless steel 20 gauge hollow needle and a second electrode 1030formed as a layer of electrically conductive material (such as silver ornickel) deposited over and adhered on an exterior surface of the needleelectrode 1020. A thin electrical insulator 1028 separates theelectrodes 1020, 1030, along their lengths to avoid short circuiting.

The electrode 1020 extends along a longitudinal axis 1072 of thefootplate 721 (FIG. 7) from a proximal region at which bipolarelectrical power is applied to a distal region of the electrodeassembly.

In a preferred embodiment, the second electrode 1030 extends over alimited portion of the circumference of the first electrode 1020, ratherthan entirely around the first electrode. Current flows over arelatively small portion of the circumference and length of the firstelectrode 1020. This limits the area in the body that receives current,and provides the operator with a high degree of control as to where thecurrent is applied. The second electrode 1030 extends over an arc ofapproximately one quarter of the circumference of the first electrode1020. The second electrode 1030 is disposed symmetrically about an axis1072.

In a preferred embodiment, the first electrode, and thus the footplate721, has a central passage 1022 that is open at the distal region,providing for irrigation and aspiration. The irrigation and aspirationlumens extend from the distal end of the probe tip 1010, through theprobe handle, to the connector, providing for irrigation and aspirationcapability.

In an embodiment as shown in FIGS. 11 a and 11 b, the electrode assemblyincludes a central or axial electrode 1120 formed by a solid cylindricalmetal member, and an elongate hollow outer electrode 1130 formed by acylindrical metal tube member, which is coaxially positioned around thecentral electrode 1120. The cylindrical outer surface of electrode 1130forms the circumferential surface of the probe. The outer electrode 1130is preferably made of stainless steel or other corrosive resistant,conductive material for strength as well as conductivity. The innerelectrode 1120 may be made of copper, but less conductive materials mayalso be employed. The coaxial relationship and spacing between theelectrodes 1120, 1130, as well as their electrical isolation from oneanother, is provided by a tubular sleeve 1128 of an electricallyinsulating material between the electrode.

A layer of insulation 1132 may also surround the second electrode 1130.One or more regions of insulating area 1132 may be removed at anysuitable location along the axis to expose a region of electrode 1130.Cauterization would occur at the exposed region. The circumferentialextent of the second electrode 1130 can be further limited, depending onthe degree of control desired over the size of the area to which currentis applied.

In an alternative embodiment, as shown in FIG. 12, the active region ata remote end of a bipolar electrode is formed by a hollow metal tube1200 having a substantially cylindrical layer of insulation 1228 on theouter surface of the metal tube. The metallic tube 1200 is not anelectrode and is provided only for the strength of the probe assembly.The tip supports two metal electrodes 1230, 1240. Each of the electrodes1230, 1240 have electric leads, which extend through the hollow interiorof the tube 1200 to a supporting insulative handle where it is coupledby appropriate means with a power source in the manner previouslydescribed. Energy flows between the electrodes 1230, 1240, heating onlythe tissue adjacent the gap therebetween. Aspiration and irrigation maybe provided through a lumen 1222.

FIGS. 13 and 14 show alternative embodiments of a goniectomycauterization probe 1300, 1400. The probe comprises a handle 1305, 1405and a probe tip 1310, 1410. The probe tip includes a cautery element1330, 1430.

The probes 1300, 1400 are provided with an energy source; however, probe1400 also includes an irrigation supply 1480 and an aspiration pump1470. These components connect to the probe 1300, 1400 at connector1308, 1408.

FIGS. 15 a,b show detailed views of probe tip 1310. The probe tip 1510is straight and includes an electrode 1530 attached to electrode 1520,which are separated by a layer of insulation 1528.

FIGS. 16 a,b show detailed views of probe tip 1410. The probe tip 1610is straight and includes an electrode 1630 attached to a hollowelectrode 1620, which are separated by a layer of insulation 1628. Thehollow electrode 1620 forms a hollow passage 1622 for irrigation andaspiration.

In an alternative embodiment, the needle tip of FIG. 14 may comprise ahollow needle, with or without a cauterizing element, acousticallycoupled to an ultrasonic handle and surrounded by a hollow sleeve. Thehandle includes an ultrasonic transducer, such as that used forphacoemulsification, which may be either piezoelectric ormagnetostrictive. When the handle is activated, the needle is vibratedlongitudinally at an ultrasonic rate. Simultaneously, a hydrodynamicflow of irrigation fluid may be introduced into the eye. The vibratingneedle emulsifies the tissue, and the particles are preferablysimultaneously aspirated, along with the fluid, out of the eye throughthe hollow needle tip. Aspiration is effected by a vacuum pump, which isconnected to the handle. The ultrasonically vibrated needle emulsifiesthe tissue by combining i) the mechanical impact of the needle tip whichvaries depending on its mass, sharpness, and acceleration, ii) theultrasonic acoustical waves generated by the metal surfaces of thevibrating needle, iii) the fluid wave created at the needle's leadingedge, and iv) implosion of cavitation bubbles created at the tip of thevibrating needle.

In an alternative embodiment, sonic technology may be used to ablate thetissue. Sonic technology offers an innovative means of removing materialwithout the generation of heat or cavitational energy by using sonicrather than ultrasonic technology. The tip expands and contracts,generating heat, due to intermolecular frictional forces at the tip,that can be conducted to the surrounding tissues. The tip does not needa hollow sleeve if sonic energy is used to remove the trabecularmeshwork.

The use of acoustic energy, and particularly ultrasonic energy, offersthe advantage of simultaneously applying a dose of energy sufficient toablate the area without exposing the eye to current. The ultrasonicdriver can also modulate the driving frequencies and/or vary power inorder to smooth or unify the produced collimated ultrasonic beam.

The amount of heat generated is directly proportional to the operatingfrequency. The sonic tip does not generate cavitational effects and thustrue fragmentation, rather than emulsification or vaporization, of thetissue takes place. This adds more precision and predictability incutting and less likelihood of damage to other areas of the eye. The tipcan be utilized for both sonic and ultrasonic modes. The surgeon canalternate between the two modes using a toggle switch on a foot pedalwhen more or less energy is required.

FIG. 17 shows the control system for a goniectomy cauterization probe.The cautery element 1730 is coupled to a cautery actuator. The cauteryactuator generally includes a radio-frequency (“RF”) current source 1760that is coupled to both the RF electrode and also a ground patch 1750which is in skin contact with the patient to complete an RF circuit, inthe case of a monopolar system. The cautery actuator may include amonitoring circuit 1744 and a control circuit 1746 which together useeither the electrical parameters of the RF circuit or tissue parameterssuch as temperature in a feedback control loop to drive current throughthe electrode element during cauterization. Also, where a plurality ofcautery elements or electrodes are used, switching capability may beprovided to multiplex the RF current source between the various elementsor electrodes.

The probe is connected to a low voltage power source via a power cordthat mates with the handle. The source may be a high frequency, bipolarpower supply, preferably, a solid state unit having a bipolar outputcontinuously adjustable between minimum and maximum power settings. Thesource is activated by an on/off switch, which may comprise a footpedal, or a button on the probe or interface. The source provides arelatively low bipolar output voltage. A low voltage source is preferredto avoid arcing between the electrode tips, which could damage the eyetissue. The generator is coupled to first and second electrodes to applya biologically safe voltage to the surgical site.

Delivery of energy to the tissue is commenced once the cautery elementis positioned at the desired location. The energy source preferablyprovides RF energy, but is not limited to RF and can include microwave,ultrasonic, coherent and incoherent light thermal transfer andresistance heating or other forms of energy as known to those of skillin the art. Energy is typically delivered to the cautery element viaelectrical conductor leads. The cautery control system may include acurrent source for supplying current to the cautery element.

The current source is coupled to the cautery element via a lead set (andto a ground patch in some modes). The monitor circuit 1744 desirablycommunicates with one or more sensors (e.g., temperature) 1730 whichmonitor the operation of the cautery element. The control circuit 1746may be connected to the monitoring circuit 1744 and to the currentsource 1760 in order to adjust the output level of the current drivingthe cautery element based upon the sensed condition (e.g. upon therelationship between the monitored temperature and a predeterminedtemperature set point).

The procedure for performing goniectomy with the goniectomycauterization probe of an embodiment of the present invention is similarto a traditional goniotomy surgery, as previously described. The surgeonpreferably sits on the temporal side of the operating room tableutilizing an operating microscope. The patient's head is rotated 45°away from the surgeon after a retrobulbar injection has anesthetized theeye. A knife, preferably 20 gauge, is used to make a clear cornealtemporal incision. The goniectomy instrument is inserted into theanterior chamber up to the infusion sleeve to maintain the intraocularpressure and deepen the anterior chamber. The surgeon positions thegonio lens, preferably a Schwann-Jacobs lens or a modified Barkangoniotomy lens, on the cornea. The goniectomy probe is advanced to thetrabecular meshwork. The sharp end point of the footplate incises themiddle one third of the trabecular meshwork, which is known as thepigmented portion of the trabecular meshwork. The footplate 721 (FIG. 7)is further inserted into Schlemm's canal. The cautery element isactivated, preferably by a footplate, which may also be used to activateirrigation and aspiration. The current provided to the cautery elementheats the tissue. The instrument is slowly advanced through thetrabecular meshwork maintaining the footplate 721 in Schlemm's canal,feeding the pigmented trabecular meshwork into the opening of theinstrument where the tissue removal occurs. The instrument is advanceduntil no further tissue can be removed inferiorly. The tissue may alsobe aspirated through the probe, thus substantially removing a portion ofthe trabecular meshwork. The instrument may be rotated in the eye andreintroduced into Schlemm's canal where the initial incision began. Thesuperior portion of the trabecular meshwork is then removed usingcautery and aspiration. In a preferred embodiment, a substantialportion, preferably at least half, of the trabecular meshwork isremoved. The corneal incision is preferably sealed by injecting abalanced salt solution into the corneal stroma or by placing a suture.The anterior chamber is reformed. A visceolastic substance may beutilized to maintain the anterior chamber with the initial incision andat the end of the surgery.

Trabeculodialysis

Trabeculodialysis is similar to goniectomy; therefore, a goniectomycauterization probe may also be used to perform trabeculodialysis. Theprocedure for performing a trabeculodialysis procedure with acauterization probe is similar to the trabeculodialysis procedurepreviously described. However, rather than cutting the tissue with aknife, the tissue is ablated with the probe. Similarly, in a preferredembodiment, a substantial portion, preferably at least half, of thetrabecular meshwork is removed.

Goniectomy Cutting Probe

Another preferred embodiment of a goniectomy cutting probe, used to cutand remove trabecular meshwork, is shown in FIG. 18. The probe comprisesa handle 1805 and a probe tip 1810. Preferably, the handle is 20 gaugeand the probe tip is approximately 25 gauge. The handle 2405 is sizedand configured to fit completely and comfortably within a hand. Thehandle 2405 may be formed of a variety of materials, including plastics,and may be designed in a variety of shapes. Generally, it will bepreferred that a convenient shape for gripping, such as a cylindricalshape, be provided. The probe tip 1810 further comprises a footplate1820, protecting endothelial cells and collector channels lining thescleral wall of Schlemm's canal. The footplate 1820 also serves as aguide in Schlemm's canal. The sharpened end of the footplate is used topenetrate the trabecular meshwork.

FIGS. 19–20 show sectional views of different embodiments of theinternal components and construction of the probe 1800. The probe isconfigured to define therewithin a hollow inner chamber. A drive member,coupled to a rotatable drive cable within a drive cable assembly, extendinto the hollow inner chamber, as shown. A rotatable drive shaft 1944,2044 is rotatably connected or engaged to the drive member, such thatthe shaft may be rotatably driven at speeds required for the trabecularmeshwork removal. The rotatable drive shaft is inserted into a boreformed in the distal face of the drive member.

The elongate rotatable drive shaft 1944, 2044 passes longitudinallythrough the probe and terminates, at its distal end, in a cutting head1945, 2045. A protective tubular sheath may be disposed about therotatable shaft. The rotatable shaft and/or sheath are axially movableso as to allow the cutting head to be alternately deployed in a) a firstnon-operative position wherein the cutting head is fully located withinthe inner bore of the tubular sheath so as to be shielded duringinsertion and retraction of the instrument or b) a second operativeposition wherein the cutting head is advanced out of the distal end ofthe sheath so as to contact and remove the trabecular meshwork. Thecutting head 1945, 2045 may be configured such that rotation of the headwill create and sustain a forced circulation of fluid within themeshwork. Such forced circulation causes the trabecular meshwork to bepulled or drawn into contact with the rotating cutting head, without theneed for significant axial movement or manipulation of the probe whilethe cutting head is rotating.

A control pedal may be connected to the motor-drive system to induceactuation/deactuation, and speed control of the rotatable drive cablewithin the drive cable assembly by the operator. Additional switches orcontrol pedals may be provided for triggering and actuating irrigationand/or aspiration of fluid and/or debris through the probe.

The probe of FIG. 19, shows the probe 1900 having two separate lumens,1922, 1924, for irrigation and aspiration. The hollow passageway 2022extending longitudinally through the probe of FIG. 20, containing therotatable drive shaft, is in fluid communication with an irrigation pump(not shown). By such arrangement, a flow of irrigation fluid may beinfused through the tube. A separate lumen 2024 is also provided foraspiration.

The independent processes of irrigation and aspiration may be performedsimultaneously with the rotation of the head or while the head is in anon-rotating, stationary mode. It will also be appreciated that theinfusion and aspiration pathways may be reversed or interchanged byalternately connecting the aspiration pump to the irrigation tubing andirrigation pump to the aspiration tubing.

In an alternative embodiment, as shown in FIGS. 21–23, the probe cutstissue in a guillotine fashion. As shown in FIG. 21, the probe 2100 mayinclude an inner sleeve 2144 that moves relative to an outer sleeve2146. The sleeves are coupled to the handle. The inner sleeve 2144 maybe coupled to a vacuum system which pulls tissue into the port 2125 whenthe inner sleeve 2144 moves away from the port. The inner sleeve 2144then moves in a reverse direction past the outer port to sever tissue ina guillotine fashion. The vacuum system draws the severed tissue awayfrom the port, so the process may be repeated. The inner sleeve may beconnected to a diaphragm and a spring, rigidly attached to the handle.The diaphragm is adjacent to a pneumatic drive chamber that is in fluidcommunication with a source of pressurized air (not shown). The drivechamber is pressurized, expanding the diaphragm. Expansion of thediaphragm moves the inner sleeve so that the tissue within the port issevered by the sleeve. Alternatively, the inner sleeve 2144 is driven bya motor located within the handle. The inner sleeve 2144 is coupled tothe motor by a rotating lever mechanism or wobble plate, inducing anoscillating translational movement of the sleeve in response to arotation of the output shaft. The motor is preferably an electricaldevice coupled to an external power source by wires that are attached toa control system at the handle.

FIG. 22 shows an embodiment wherein the irrigation lumen 2222 containsthe cutting sleeve 2244. Cutting sleeve 2244 has a cutting blade 2245integrally formed at its distal end. FIG. 23 shows an alternativeembodiment, wherein the irrigation lumen 2322 does not contain thecutting sleeve. An aspiration lumen 2224, 2324 is also provided. Theaspiration line may be directly coupled to an aspiration pump; theirrigation lumen may be directly coupled to an irrigation pump.

The procedure for goniectomy with the goniectomy cutting probe issimilar to the goniectomy procedure discussed for the goniectomycauterization probe. However, rather than cauterizing the trabecularmeshwork, the tissue is cut using a rotatable blade or cut in aguillotine fashion, and subsequently aspirated. In a preferredembodiment, a substantial portion, preferably at least half, of thetrabecular meshwork is removed.

Goniectomy Laser Probe

A laser probe 2400, as shown in FIGS. 24 a and 24 b, is provided toablate the trabecular meshwork. The probe 2400 comprises a handle 2405and a probe tip 2410. The handle 2405 is sized and configured to fitcompletely and comfortably within a hand. It will be understood that thehandle 2405 may be formed from a variety of materials, includingplastics, and may be designed in a variety of shapes. Generally, it willbe preferred that a convenient shape for gripping, such as a cylindricalshape, be provided. The main body of the handle 2405 comprises a plastichousing within which a laser system is contained. The plastic housing isprovided to enable easy manipulation of the handle 2405 by the user. Thelaser is preferably an excimer laser.

FIG. 24 a shows an embodiment wherein the laser source is containedwithin the probe, but rather within the control system. A fiber isprovided to direct the light energy from the source to the proximal endof the probe tip. The laser radiation is generated in close proximity tothe eye, so that relatively little laser light is lost duringtransmission.

FIG. 24 b shows an embodiment wherein the laser source is not containedwithin the probe. The source may include a longitudinal flashlamp. Afiber is provided to direct the light energy from the source to theproximal end of the probe tip.

The probe tip 2410 is connected to the main body 2405. The probe tipcomprises a footplate to protect the outer wall of Schlemm's canal, suchthat only the tissue of the trabecular meshwork is cauterized. Thefootplate also is used to penetrate the trabecular meshwork and servesas a guide in Schlemm's canal. In general, the probe tip 2410 isstraight or curved.

FIG. 25 shows a detailed view of FIG. 24 a. The handle includes areflective tube 2508 which has a mirrored inside surface. An Er: YAG rod2513 is located along the axis of the tube 2508. The pump for the laserlight source is preferably a high pressure flashtube 2512 or a similarsuitable light source which is located adjacent the rod 2513 within thereflective tube 2508. The flashtube 2512 produces very brief, intenseflashes of light, there being approximately 10 to 100 pulses per second.

Er:YAG rods generate an output wavelength of approximately 2.94 microns.Use of an erbium doped laser, such as an Er: YAG laser, is advantageousbecause it requires less power to ablate the eye tissue than do the Nd:YAG and Holmium:YAG lasers of the prior art. Preferably the Er: YAGlaser has a pulse repetition rate of 5 to 100 Hz, a pulse duration of250 μs to 300 μs, and a pulse energy of 10 to 14 mJ per pulse. Using anEr: YAG laser at the above parameters limits the thermal damage ofsurrounding tissue to a depth of 5 to 50 microns. By reducing thethermal damage of surrounding tissue, the amount of scar tissue buildupcaused by the laser is minimal. Thus, the likelihood that the passagewaywill become blocked with scar tissue is reduced, and the likelihood thatthe procedure will need to be repeated is reduced.

The reflective inner surface 2546 of the tube 2508 serves to reflectlight from the flashlamp 2512 to the rod 2513. Reflection of the lightby the cylindrical mirror focuses as much light as possible toward therod 2513. This results in efficient coupling between the light source2512 and the laser rod 2513. Thus, essentially all light generated inthe flashtube 2512 is absorbed by the laser rod 2513.

The rod 2513 has a totally reflective mirror 2514 and output mirror 2517at its two ends. The mirror 2514 at the proximal end of the rod 2513provides 100% reflection of light back to the rod 2513. At the remoteend of the rod 2513, the output mirror 2517 provides less than 100%reflection. Thus, while most of the light energy directed toward theoutput mirror 2517 of the rod 2513 is reflected back into the rod 2513,intensifying the beam, some of the waves of energy pass through theoutput mirror 2517 and into the transmission system 2511 for conductingit toward the probe tip 2515. A reflective coating on the end of thelaser rod 2513 may be used to supplement or replace the mirrors 2517,2514.

The mirrors 2517, 2514 on either end of the rod form a resonator.Radiation that is directed straight along the axis of the rod 2513bounces back and forth between the mirrors 2517, 2514 and builds astrong oscillation. Radiation is coupled out through the partiallytransparent mirror 2517.

The transmission system 251 is preferably an optical fiber. Preferably,a sapphire or fused silica fiber will be used with the laser, containedwithin the handle. A germanium oxide Type IV fiber is also suitable forcarrying erbium laser light with reduced attenuation. It is alsopossible to deliver laser light through hollow waveguides. Suchwaveguides often include multi-layer dielectric coatings to enhancetransmission.

FIG. 26 shows a detailed view of one embodiment of a probe tip 2600, inwhich the fiber 2610 is centrally located within the probe tip 2600.

Alternatively, the probe tip may be hollow, forming anaspiration/irrigation lumen (not shown). The lumen extends the entirelength of the probe. Alternatively, as shown in FIG. 27, the lumen 2722may extend adjacent the probe tip 2710. The aspiration lumen 2722communicates with a vacuum source for withdrawal of emulsified materialthrough an aperture or aspiration port. During use, the vacuum sourcecan be employed to aspirate material which has been fragmented orablated by the pulsed laser light. The vacuum source can also be used todraw the tissue into close proximity with the delivery end of the probethereby facilitating its destruction. Fluid introduced through thelumen, chamber, and aperture can provide for flushing of the site andreplacement of lost volume due to removal of the emulsified material.

The probe is inserted under direct vision to ablate the trabecularmeshwork for use in treating glaucoma, thus obtaining a free flow ofaqueous from the anterior chamber into Schlemm's canal and through thecollector channels. The end of the probe is inserted through arelatively small incision in the eye, and can be maneuvered very closeto the tissue to be emulsified.

The procedure is similar to the goniectomy procedure previouslydiscussed with reference to the goniectomy cauterization probe. Thesurgeon visualizes the trabecular meshwork under direct microscopy andengages the superficial layers of the meshwork at the midpoint of thetrabecular band, by placing the tissue between the end 2521 of the fiber2511 and the probe tip (footplate) 2519. Once inserted, the fiber 2511is positioned to focus laser energy directly on the trabecular meshwork.The probe tip 2519 absorbs any laser energy which is not absorbed by thetrabecular meshwork, thus protecting Schlemm's canal from damage. Lightis transmitted to and through the probe, and the tissue is ablated. Thearea may be irrigated and aspirated, removing the tissue from the eye.In a preferred embodiment, a substantial portion, preferably at leasthalf, of the trabecular meshwork is removed. After treatment, the probeis readily withdrawn from the eye. Leakage may be stopped using a sutureand burying the knot.

Laser treatment with an Er:YAG laser is advantageous because aswavelength increases, contiguous thermal effects decrease. In thevisible portion of the spectrum, water has minimal absorption. Above 2.1μm however, this absorption increases to a level comparable to excimerlasers operating around 200 nm. This increase is quite rapid. A markeddifference therefore exists between radiation at 2.79 μm and 2.94 μm.This confines the energy delivered to a smaller volume, allowing moreablation to occur at lower total energy levels and limiting contiguousthermal damage. Er: YAG lasers produce ablations with minimal amounts ofcontiguous thermal damage. Light in the infrared region has anadditional advantage over ultraviolet radiation in that it is not knownto have mutagenic or carcinogenic potential.

Due to the large absorption band of the water at the wavelength of theerbium laser, no formation of sticky material on the probe tip takesplace, which can be a serious problem at other wavelengths.

Schlemmectomy Cauterization Probe

Schlemmectomy is a new surgical procedure, similar to trabeculotomy.However, in a schlemmectomy procedure, disrupted tissue is removed usinga schlemmectomy cauterization probe. FIG. 28 illustrates a probe 2800 inaccordance with this invention for removal of the trabecular meshwork,using a cautery element 2830 on a probe similar to a traditionaltrabeculotome, such as Harm's trabeculotome. The probe uses both cauteryand mechanical disruption to ablate the fibers of the trabecularmeshwork, leaving a patent open Schlemm's canal.

The probe 2800 comprises a handle 2805 and a probe tip 2810. Theproximal end of the handle is adapted for mating with a connector 2812to the output terminals of an energy source 2860.

The probe also includes electrical leads 2934 (FIG. 29), a power cable2808, preferably a coaxial cable, and an actuator. These componentsextend from the handle 2805, through an electrical lead lumen 2932 (FIG.29) in the probe shaft 2805, to the corresponding components of theprobe 2800 disposed on the distal end. The proximal ends of the cablesand lumens connect to the corresponding connectors that extend from thedistal end of the probe handle 2805.

FIGS. 29 a–c illustrate one probe tip configuration. The probe tip 2910comprises two parallel arms 2920, 2950. The probe tip 2910 comprises anelectrode 2930, which will be described in further detail below,disposed on the lower arm 2920. The probe tip 2910 comprises anelectrical lead lumen 2932 which extends the length of the probe tip2910 from the electrode 2930 through the cylindrical body 2802 to theconnector of the probe handle 2812. (FIG. 28)

FIG. 30 shows a preferred embodiment of a probe 3000. The probe of FIG.30 is similar to the probe of FIG. 28, except that probe 3000 furthercomprises irrigation means. Irrigation may be provided by an irrigationpump 3080 or hydrostatic pressure from a balanced salt solution bottleand tubing.

In a preferred embodiment, as shown in FIG. 31 a, the irrigation lumen3122 is situated at the end of the probe. Irrigation under pressureflushes blood from the eye and expands Schlemm's canal and the anteriorchamber, providing more room for the procedure. Alternatively, lumen3122 provides for aspiration by connecting the lumen to an aspirationpump. Aspiration ports may be provided equidistantly along the length ofthe cauterizing element of the trabeculotome, as shown in FIG. 31 b. Inan embodiment, as shown in FIG. 31 c, two lumens are provided, anirrigation lumen 3122 and an aspiration lumen 3124. Two separate lumensprovide for simultaneous irrigation and aspiration.

With reference to the schlemmectomy probes of FIGS. 28 and 30, thehandle 2805, 3005 may be made of an electrically insulating polymericmaterial, configured in a pencil-shape form having a cylindrical bodyregion 2802, 3002 and a tapered forward region 2804, 3004. Although apencil-shape configuration is preferred, it is noted that anyconfiguration of the handle 2805, 3005 which is easily, comfortably andconveniently grasped by the operator will also be suitable and isconsidered to be within the scope of the present invention.

The probe tip 2810, 3010 is connected to the main body of the handle2805, 3005. The cautery element 2830, 3030 at the distal end of theprobe tip 2810, 3010 can have a variety of configurations.

The tip 2810, 3010 may be any material, such as titanium, brass, nickel,aluminum, stainless steel, other types of steels, or alloys.Alternatively, non-metallic substances may also be used, such as certainplastics. The tip may be conductive or non-conductive, depending on thespecific embodiment, as will be discussed.

FIGS. 32 a and 32 b show alternative distal probe tip configurations,wherein the second electrode 3230 extends along the entire length of thefirst electrode 3220. The probe tip 3210 may be curved to bettermaneuver within the anatomy of the eye. The malleable probe tips can beconfigured as straight, angled or curved, for example, which providesfor optimal access to specific anatomy and pathology. Unique tip designsimprove tactile feedback for optimal control and access, and provide forimproved tissue visualization with greatly reduced bubbling or charring.

Referring again to the probes of FIGS. 28 and 30, the probe tip 2810,3010 comprises an electrode or cautery element 2830, 3030, suitable forcautery, as known to those of skill in the art. Various electrodeconfigurations and shapes may be suitable. The cautery element 2830,3030 is any electrode that may provide ablation or cauterization oftissue, such as a RF electrode, an ultrasound transducer, or any othersuitable electrode. Alternatively, or in addition to the RF electrodevariations, the cautery element may also include other cautery energysources or sinks, and particularly may include a thermal conductor.Examples of suitable thermal conductor arrangements include a metallicelement which may, for example, be constructed as previously described.In the thermal conductor embodiment such a metallic element would begenerally resistively heated in a closed loop circuit internal to theprobe, or conductively heated by a heat source coupled to the thermalconductor.

The electrode 2830, 3030 may be provided on the inner surface of thetip. Alternatively, the electrode 2830, 3030 may be embedded in a sheathof a tube. Insulation may be provided around the cautery element so thatother areas of the eye are not affected by the cauterization. A sleeveshield or a non-conductive layer may also be provided on the probe tipto expose only a selected portion of the electrode. The sleevepreferably has sufficient thickness to prevent both current flow andcapacitance coupling with the tissue.

The cautery element can be made of a number of different materialsincluding, but not limited to stainless steel, platinum, other noblemetals, and the like. The electrode can also be made of a memory metal,such as nickel titanium. The electrode can also be made of compositeconstruction, whereby different sections are constructed from differentmaterials.

In a preferred embodiment of an RF electrode, the electrode system isbipolar. In a bipolar system, two electrodes of reversed polarity arelocated on the probe tip and RF energy bridges the electrodes.Additionally, any number of pairs of electrodes may be provided on theprobe tip.

In an alternative RF electrode embodiment, the electrode system ismonopolar. In a monopolar system, the system comprises a singleelectrode and a contact plate. The contact plate is attached to thesurface of the human body. The contact plate is further connected to thereturn terminal of the power source via a lead wire. Voltages of reversepolarity are applied to the electrode and the contact plate.

In a preferred embodiment, as shown in FIGS. 33 a and 33 b, an electrodeassembly of a bipolar probe includes one electrode 3320 made from astainless steel 20 gauge hollow needle and a second electrode 3330formed as a layer of electrically conductive material (such as silver ornickel) deposited over and adhered to an exterior surface of the needleelectrode. A thin electrical insulator 3324 separates the electrodes3320, 3330, along their lengths to avoid short circuiting.

The electrodes 3320, 3330 extend along a longitudinal axis 3372 of theinstrument from a proximal region at which bipolar electrical power isapplied to a distal region of the electrode assembly.

In a preferred embodiment, the second electrode 3330 extends over alimited portion of the circumference of the first electrode 3320, ratherthan entirely around the first electrode 3320. Current flows from therelatively small portion of the circumference of the second electrode3330 where heat is generated in the adjacent tissue, and into the layersurface of the first electrode 3320, where little heat is generated.This limits the area in the body that receives dense current, andprovides the operator with a high degree of control as to where thecurrent is applied. The second electrode 3330 extends over an arc ofapproximately one quarter of the circumference of the first electrode.The second electrode 3330 is disposed symmetrically about an axis 3372.

In a preferred embodiment, the first electrode 3320 has a centralpassage 3322 that is open at the distal region, providing forirrigation. The irrigation lumen 3322 extends from the distal end of theprobe tip, through the probe handle, to the connector, providing forirrigation capability.

FIG. 34 shows an alternative embodiment, wherein the electrode assemblyincludes a central or axial electrode 3420 formed by a solid cylindricalmetal member, and an elongate hollow outer electrode 3430 formed by acylindrical metal tube member, which is coaxially positioned around thecentral electrode. The cylindrical outer surface of electrode 3430 formsthe circumferential surface of the probe. The outer electrode 3430 ispreferably made of stainless steel or other corrosive resistant,conductive material for strength as well as conductivity. The innerelectrode 3420 may be made of copper, but less conductive materials mayalso be employed. The coaxial relationship and spacing between theelectrodes, as well as their electrical isolation from one another, isprovided by a tubular sleeve 3424 of an electrically insulating materialbetween the electrode, completing the probe assembly. An additionallayer of insulation 3434 may be provided on outer electrode 3430 toexpose only a limited portion of the electrode to concentrate RF energyat the limited exposed region.

Alternatively, one or more regions of insulating area 3434 may beremoved at any suitable location along the axis to expose a region ofelectrode 3430. Cauterization would then occur at the exposed region.The circumferential extent of the second electrode 3430 can be furtherlimited, depending on the degree of control desired over the size of thearea to which current is applied.

In an alternative embodiment as shown in FIGS. 35 a and 35 b, the activeregion of a bipolar electrode probe assembly is formed by a hollow metaltube 3515 having a substantially semi-cylindrical sleeve 3524 on tube3515. The metallic tube 3515 is not an electrode and is provided onlyfor the strength of the probe assembly. The tip supports two cauteryelements 3520, 3530. Each of the elements 3520, 3530 is connected toelectrical leads, which extend through the hollow interior of the tip3510 to a supporting insulative handle where it is coupled byappropriate means with a power source in the manner previouslydescribed.

The probe is connected to a low voltage RF power source via a power cordthat mates with the handle. The source may be a high frequency, bipolarpower supply, preferably, a solid state unit having a bipolar outputcontinuously adjustable between minimum and maximum power settings. Thesource is activated by an on/off switch, which may comprise a footpedal, or a button on the probe or interface. The source provides arelatively low bipolar output voltage. A low voltage source is preferredto avoid arcing between the electrode tips, which could damage the eyetissue. The RF generator is coupled to first and second electrodes toapply a biologically safe voltage to the surgical site. This probe hasthe advantage of cauterizing at both of the bipolar elements, each ofwhich has a limited, RF current concentration area.

Delivery of energy to the tissue is commenced once the cautery elementis positioned at the desired location. Energy is typically delivered tothe cautery element via electrical conductor leads. The energy sourcepreferably provides RF energy, but is not limited to RF and can includemicrowave, electrical, ultrasonic, coherent and incoherent light thermaltransfer and resistance heating or other forms of energy, as known tothose of skill in the art.

The cautery actuator may include a monitoring circuit 1744 and a controlcircuit 1746 (FIG. 17) which together use either the electricalparameters of the RF circuit or tissue parameters such as temperature ina feedback control loop to drive current through the electrode elementduring cauterization. Feedback control systems can be used to obtain thedesired degree of heating by maintaining the selected sight at a desiredtemperature for a desired time. A sensor, such as a thermocouple may beused to monitor temperature in a feedback loop. Where a plurality ofcautery elements or electrodes are used, switching capability may beprovided to multiplex the RF current source between the various elementsor electrodes.

FIG. 17 shows the monitor circuit 1744, which desirably communicateswith one or more sensors (e.g., temperature) 1740 which monitor theoperation of the cautery element 1730. The control circuit 1746 may beconnected to the monitoring circuit 1744 and to the current source inorder to adjust the output level of the current driving the cauteryelement 1730 based upon the sensed condition (e.g. upon the relationshipbetween the monitored temperature and a predetermined temperature setpoint).

Circuitry, software and feedback to a controller, which result in fullprocess control, may be used to change (i) power—including RF,incoherent light, microwave, ultrasound, and the like, (ii) the dutycycle, (iii) monopolar or bipolar energy delivery, (iv) fluid(electrolyte solution delivery, flow rate and pressure) and (v)determine when ablation is completed through time, temperature and/orimpedance.

In a preferred embodiment, a bipolar electrode is part of a circuit thatincludes the RF signal generator, connecting cables, probe tip forinsertion into the eye, a grounding electrode attached to the probe anda return cable that connects the grounding electrode to the RF generatorcompleting the circuit. Because such a RF electrode is a relatively goodconductor, the electrode itself does not heat up. The tissues that theelectrode comes in contact with heat up in response to current passingfrom the electrode through the tissues. The tissue heats up because itis a relatively poor conductor as compared to the rest of the circuit.It is when the tissues heat up as a result of molecular friction, thatheat is then conducted back to the electrode itself. At that point, athermocouple senses the increase in temperature and supplies thatinformation to the RF generator so that the feedback mechanism canattenuate the energy delivered in order to attain temperature control.

It may also be advantageous to regulate RF delivery through bothtemperature and impedance monitoring. It may also be advantageous tomonitor irrigation fluid flow to maintain clarity at the site. There isalso an opportunity for synergy between RF and irrigation fluid deliveryto the surgical site to provide, for example, a greater level of controlof temperatures at the site.

The controller may include an RF generator, temperature profile,temperature regulator, temperature monitor, surgical instrument,impedance monitor, impedance regulator, pump, flow regulator and flowmonitor.

The RF generator may be capable of delivering monopolar or bipolar powerto the probe. The probe is positioned at the surgical site. Theimpedance monitor obtains impedance measurements by, for example,measuring current and voltage and performing a RMS calculation. Themeasurements of the impedance monitor are delivered to the impedanceregulator. The impedance regulator performs several functions. Generallythe impedance regulator keeps the impedance levels within acceptablelimits by controlling the power supplied by the RF generator. In oneembodiment of the current invention the impedance regulator can controlthe flow regulator to deliver more or less irrigation fluid to thesurgical site.

To maintain the appropriate temperature for cauterizing tissue, thedistal tip of the probe may also be equipped with a thermocouple 1740.Temperature feedback, in combination with a timing device, permits aprecise degree of cautery to be delivered, obtaining the desired effectwithout causing any intraocular heating. The heating effect on tissuemay be mitigated with a viscoelastic agent to deepen the anteriorchamber.

Referring to FIG. 17, the temperature monitor 1744 may include one ormore types of temperature sensors, e.g. thermocouples, thermistors,resistive temperature device (RTD), infrared detectors, etc.

Suitable shapes for the thermocouple include, but are not limited to, aloop, an oval loop, a “T” configuration, an “S” configuration, a hookconfiguration or a spherical ball configuration. These shapes providemore surface area for the thermocouple without lengthening thethermocouple. These thermocouples, with more exposed area than astraight thermocouple, are believed to have better accuracy and responsetime. The thermocouple is attached by a fastener. The fastener may be abead of adhesive, such as, but not limited to, epoxies, cyanoacetateadhesives, silicone adhesives, flexible adhesives, etc. It may also bedesirable to provide multiple thermocouples at different locations andcompare their operating parameters (e.g. response times, etc.), whichmay provide useful information to allow certain such variables to befiltered and thereby calculate an accurate temperature at thethermocouple location.

The output of the temperature monitor 1744 is delivered to thetemperature regulator 1746. The temperature regulator 1746 may controlboth the RF generator 1760 and the flow regulator. When, for example,temperatures have increased beyond an acceptable limit, power suppliedby the RF generator to the surgical instrument may be reduced.Alternately, the temperature regulator may cause the flow regulator toincrease irrigation fluid, thereby decreasing the temperature at thesurgical site. Conversely, the temperature regulator can interface witheither the RF generator or the flow regulator when measured temperaturesdo not match the required temperatures. The flow regulator interfaceswith the pump to control the volume of irrigation fluid delivered to thesurgical site.

The procedure for performing a Schlemmectomy with the probe of thepresent invention is similar to a traditional trabeculotomy procedure,as previously described. The surgeon preferably sits on the temporalside of the operating room table utilizing the operating microscope. Aninfrotemporal fornix based conjunctival flap is made and the conjunctiveand Tenons capsule are mobilized posteriorly. A triangular flap is madeand the superficial flab is mobilized into the cornea. A radial incisionis made over the canal of Schlemm, thus creating an entrance into thecanal. Vanna scissors are preferably introduced into the Schlemm'scanal, opening the canal for approximately 1 mm on either side. A clearcorneal parenthesis is performed and the anterior chamber is deepened,preferably with Haelon GV. The probe is introduced into Schlemm's canalinferiorly. The instrument is now aligned such that the cauterizationelement faces into the deepened anterior chamber. Alternatively, thecauterization surface faces the trabecular meshwork and is activated bythe foot switch at the time of the rotation of the probe into theanterior chamber. The foot switch may then be used to activatecauterization. Aspiration and irrigation may also be activated using thefoot switch. The trabeculotome is slowly rotated into the anteriorchamber and when the blade of the trabeculotome is seen in the anteriorchamber, the cautery (and aspiration and/or irrigation) are deactivated.The superior aspect of Schlemm's canal may be entered with atrabeculotome having the opposite curvature. Following the same steps,more of the trabecular meshwork is removed. In a preferred embodiment, asubstantial portion, preferably at least half, of the trabecularmeshwork is removed. After removing the trabeculotome, the superficialtrabeculotomy flap is sutured closed using sutures.

Radiowave surgery uses high frequency radio waves instead of heat to cutand coagulate tissue without the burning effect that is common withtraditional electrosurgical devices and cautery equipment. Theresistance of tissue to the spread of radio wave energy produces heatwithin the cell, causing the water within the cell to volatilize anddestroy the cell without damaging other cellular layers.

While particular forms of the invention have been described, it will beapparent that various modifications can be made without departing fromthe spirit and scope of the invention. Accordingly, it is not intendedthat the invention be limited, except as by the appended claims.

1. A device for treating glaucoma, said device comprising: an elongateprobe; a bipolar electrode that is useable to form an opening in thetrabecular meshwork such that fluid may drain through said opening intoSchlemm's canal; and, a protector configured to be advanced intoSchlemm's canal, said protector being configured and positioned inrelation to the bipolar electrode such that the protector willsubstantially protect cells lining the scleral wall of Schlemm's canalfrom being substantially damaged by energy that emanates from thebipolar electrode.
 2. A device according to claim 1 wherein theprotector comprises a foot plate.
 3. A device according to claim 1wherein the protector is non-parallel to a longitudinal axis of theelongate probe.
 4. A device according to claim 1 wherein the elongateprobe comprises a proximal portion and distal portion, the distalportion comprising the protector, said distal portion being non-parallelto the proximal portion.
 5. A device according to claim 1 wherein theprobe is substantially L-shaped, having a proximal portion and a distalportion, wherein the distal portion comprises the protector, said distalportion being generally perpendicular to the proximal portion.
 6. Adevice according to claim 1 further comprising at least one lumenextending through at least a portion of the probe, said at least onelumen terminating in at least one port that becomes positioned withinthe eye during operation of the device.
 7. A device according to claim 4comprising an irrigation lumen that terminates in an irrigation port andan aspiration lumen that terminates in an aspiration port.
 8. A systemcomprising a device according to claim 1 in combination with a powersource for delivering power to said bipolar electrode.
 9. A systemaccording to claim 8 wherein the bipolar electrode is useable tosubstantially ablate at least a portion of the trabecular meshwork. 10.A device according to claim 1 wherein the probe comprises a handleconfigured to be grasped by the human hand.
 11. A device according toclaim 10 further comprising at least one switch on said handle for atleast actuating and deactuating the bipolar electrode.
 12. A systemcomprising a device according to claim 1 further comprising a foot pedalin communication with said device, said foot pedal being usable for atleast actuating and deactuating the bipolar electrode.
 13. A deviceaccording to claim 1 wherein the protector has a tip that is configuredto penetrate trabecular meshwork, thereby facilitating advancement ofthe protector into Schlemm's canal.